A valve timing regulation device is provided to a power transmission path transmitting a power from a drive shaft to a driven shaft of an internal combustion engine, and regulates valve timing of an inlet valve and an exhaust valve driven to open and close by the driven shaft. A hydraulic valve timing regulation device includes a housing rotating in association with one of the drive shaft and the driven shaft, and a vane rotor fixed to an end of the other one of the drive shaft and the driven shaft. The vane rotor divides an interior of the housing into a first hydraulic chamber and a second hydraulic chamber. By supplying a hydraulic oil to one of the first hydraulic chamber and the second hydraulic chamber, the vane rotor is rotated relative to the housing in an advance direction or a retard direction. The hydraulic oil is supplied by an oil passage switching valve.
A valve timing regulation device disclosed in Patent Literature 1 has an oil passage switching valve which is a spool valve provided to a center part of the vane rotor. The oil passage switching valve includes a sleeve having various ports, and a spool moving axially in the sleeve.
The sleeve is formed in a cylindrical shape to extend axially and has a supply port, a first drain port, a first control port, a second control port, and a second drain port, which are provided sequentially from a camshaft side. The supply port communicates with a supply oil passage of the camshaft. The first drain port communicates with a drain oil passage which radially penetrates through the camshaft. The first control port communicates with the first hydraulic chamber. The second control port communicates with the second hydraulic chamber. The second drain port communicates with a drain space located outside on an opposite side to the camshaft with the vane rotor in between.
The spool has a connection oil passage provided to a shaft center part to connect the supply port to either the first control port or the second control port according to an own axial position.
When the hydraulic oil is supplied to the first hydraulic chamber, the oil passage switching valve connects the second control port to the second drain port while connecting the supply port to the first control port. In such a circumstance, the hydraulic oil in the second hydraulic chamber is discharged to the drain space from the second drain port. Meanwhile, when the hydraulic oil is supplied to the second hydraulic chamber, the oil passage switching valve connects the first control port to the first drain port while connecting the supply port to the second control port. Hydraulic oil in the first hydraulic chamber is discharged to an outside from a discharge hole opening in an outer peripheral surface of the camshaft.